Mercurial > sdl-ios-xcode
view docs/man3/SDL_CDtrack.3 @ 1544:ab1e4c41ab71
Fixed bug #33
Mike Frysinger wrote:
> with libsdl-1.2.9, some games (like bomberclone) started
> segfaulting in Gentoo
[...snip...]
> the last change in the last hunk:
[...snip...]
> if i change the statement to read:
> (table[which].blit_features & GetBlitFeatures()) == GetBlitFeatures()
> bomberclone no longer segfaults on my box
Alex Volkov wrote:
> The test "(table[which].blit_features & GetBlitFeatures()) ==
> table[which].blit_features)" is correct, and the previous
> "(table[which].cpu_mmx == SDL_HasMMX())" was actually broken.
I think there is potentially a slightly different cause of the above problem.
During the introduction of the Altivec code, the blit_table struct field
'alpha' got changed from a straightforward enum to a bitmask, which makes
perfect sense by itself. However, now the table driven blitter selection code
in SDL_CalculateBlitN() can choose the wrong blitters when searching for a
NO_ALPHA blitter because of the following code:
int a_need = 0;
...
(a_need & table[which].alpha) == a_need &&
When searching through the normal_blit_2[] table, a SET_ALPHA blitter (like
Blit_RGB565_ARGB8888) can now be selected instead of a NO_ALPHA one, causing
alpha channel bits to appear in a non-alpha destination surface. I suppose this
could theoretically be an indirect cause of the segfault mentioned above.
I *think* this can be fixed by changing to
int a_need = NO_ALPHA;
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Wed, 15 Mar 2006 15:47:49 +0000 |
parents | e5bc29de3f0a |
children | 546f7c1eb755 |
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.TH "SDL_CDtrack" "3" "Tue 11 Sep 2001, 22:59" "SDL" "SDL API Reference" .SH "NAME" SDL_CDtrack\- CD Track Information Structure .SH "STRUCTURE DEFINITION" .PP .nf \f(CWtypedef struct{ Uint8 id; Uint8 type; Uint32 length; Uint32 offset; } SDL_CDtrack;\fR .fi .PP .SH "STRUCTURE DATA" .TP 20 \fBid\fR Track number (0-99) .TP 20 \fBtype\fR \fBSDL_AUDIO_TRACK\fP or \fBSDL_DATA_TRACK\fP .TP 20 \fBlength\fR Length, in frames, of this track .TP 20 \fBoffset\fR Frame offset to the beginning of this track .SH "DESCRIPTION" .PP \fBSDL_CDtrack\fR stores data on each track on a CD, its fields should be pretty self explainatory\&. It is a member a the \fI\fBSDL_CD\fR\fR structure\&. .PP .RS \fBNote: .PP Frames can be converted to standard timings\&. There are \fBCD_FPS\fP frames per second, so \fBSDL_CDtrack\fR\&.\fBlength\fR/\fBCD_FPS\fP=length_in_seconds\&. .RE .SH "SEE ALSO" .PP \fI\fBSDL_CD\fR\fR ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:59